Previous attempts have been made in the prior art to produce a fire-resisting glass window containing an aqueous gel or liquid medium between fire resistant glass sheets. The aqueous gel contained mineral salts or polymer able to produce an insulating foam under the effect of heat radiation. Thus, the gel polymerizes when exposed to fire, thereby producing an insulating foam. The addition of mineral salts, however, quickly resulted in a drop in the optical qualities of the fire resistant glass window, i.e. especially a drop in the transparency.
Another defect of multiple panes of fire resistant glass windows containing an aqueous gel between the glass sheets is the gel mobility or fluidity when the glass is subject to fire's extreme temperatures. In the case of fire, it has been found that the gel has a tendency to collapse and expand, thereby forming relatively large aerated zones. Often the collapse and expansion continues until one large aerated zone is formed. Meanwhile, the panes exposed to the fire deform, break and finally fall away from the door.
Additional considerations arise when a multiple pane fire resistant window is subject to repeated shocks as in its role as the main element of a fireproof door. Door mounted aqueous film-multiple pane units are subject to bubbling after a certain number of jarring shocks. The bubbles can possess relatively large volumes and are mobile along the inside surfaces of the glass sheets. Thus, the aqueous film is detachable from a glass sheet's inside face. The combination of the above traits results in an aqueous gel-multiple pane door which exhibits poor fireproofing properties.
High temperature glasses have been developed based on lithium alumina silicates and other high temperature glass which are difficult to manufacture and expensive in general and also are difficult to make in sizes larger than 30″ wide. These are still limited in that they also still melt slowly at the temperature of the required testing and therefore still have difficulty meeting the 900° C. flame test for 1 hour and do not insulate the back pane of the window causing excessive heat transfer. In addition, the haze levels of this glass are higher than standard window panes (reduced transparency).
U.S. Pat. No. 4,264,681 to Girard et al, which is herein incorporated by reference, relates to fire resistant windows having spaces filled with an aqueous gel consisting of organic titanates, organic zirconates and silanes. The gel tends to bubble under jarring shock.
U.S. Pat. No. 5,449,560 to Antheunis, which is herein incorporated by reference, relates to liquid curable compositions prepared from polydialkylsiloxanes and polyhydrogen organosilanes as an interlayer for a laminate of glass.
U.S. Pat. No. 5,124,208 to Bolton et al, which is herein incorporated by reference, relates to a window assembly which can be used by the present invention.
Other fire resistant windows of interest include U.S. Pat. Nos. 7,090,906; 6,159,606; 5,885,713; 5,543,230 and 5,696,288, which are herein incorporated by reference.
PCT/US2008/011144 which is herein incorporated by reference, discloses anti-spall windows which can be used in the present invention.
It is understood that the term “plastic layer” includes polymeric sheets or films which are single layers or laminates of one or more sheets or films